新型二苯甲酮光引发剂的合成及其光聚合性能

本文合成了一种新型二苯甲酮基复合光引发剂4-(2-羟基-3-叔丁基)二苯甲酮(OEBP),采用红外光谱、核磁共振氢谱对其结构进行表征。并采用实时红外光谱研究了OEBP光引发剂引发丙烯酸酯类单体的光聚合行为。结果表明,该引发剂的最大吸收光谱在280 nm,随着紫外光照的进行,OEBP的最大吸收峰280 nm逐渐减少,其变化呈线性关系。随着引发剂浓度的增加,单体的最大速率和转化率先增大后减小;随着光强的增大,单体转化率和最大聚合速率都增大。OEBP与传统的光引发剂二苯甲酮/4-二甲基氨基苯甲酸乙酯(BP/EDAB)引发效率相当。     

光敏有机硅聚氨酯丙烯酸酯预聚体光聚合性能的研究

采用实时红外法（Real time infrared spectrum,RTIR）详细研究了光引发剂及活性单体对光敏有机硅聚氨酯丙烯酸酯（Polysiloxane urethane acrylate,PSUA）体系的光聚合性能的影响。研究发现,断裂型光引发剂的引发效率要高于夺氢型的光引发剂的引发效率,其中Irgaeure 1700引发体系的聚合速率最快。光引发剂最佳用量为0．5％～1％。体系的双键转化率随单体官能度的增加而降低。含单体HEA和IBOA的感光体系的双键转化率最大,基本完全聚合;而含TPGDA和HDDA的体系的双键转化率大约在90％～95％之间;含TMPTA的体系的双键转化率只有80％左右。含不同活性单体体系的双键转化速率的大小顺序为：TPGDA≈HDDA〉HEA〉TMPTA〉IBOA,体系的双键转化率和双键转化速率都随着单体含量的增加而减小。     

丙烯酸酯单体的邻氯代六芳基双咪唑复合光引发聚合动力学研究

利用紫外光谱对2,2’-二邻氯苯基．4,4’,5,5＇-四苯基-1,2’-二咪唑（BCIM）光引发剂开展研究。以BCIM为光引发剂、4,4-二（N,N＇-二甲基．氨基）苯甲酮（EMK）为光增感剂,N-苯基甘氨酸（NPG）为供氢体,通过实时红外光谱（RT-IR）研究丙烯酸酯单体在复合光引发体系中的光聚合动力学。结果表明：引发剂浓度越大,聚合速率越快,双键转化率越高;复合光引发体系中,当质量比mfBCIM：m（EMK）：m（NPG）：10：5：5时,引发效率最高（96．7％）;双官能度单体引发效率较三官能度的好,双键转化率可达90％以上;聚合速率随光照强度的增强而变快。     

4-(2-甲基丙烯酰氧基)甲基二苯甲酮光引发剂的合成及其光聚合动力学研究

以4-甲基二苯甲酮和2-甲基丙烯酸为原料合成了可聚合光引发剂4-(2-甲基丙烯酰氧基)甲基二苯甲酮(4-MAMBP),利用核磁共振仪和紫外吸收光谱进行了表征;选取三羟甲基丙烷三丙烯酸酯(TMPTA)曝光聚合,利用铅笔硬度法测试了固化膜的硬度;运用实时红外(RT-IR)进行光聚合反应动力学研究,考察了单体、光强及引发剂浓度对聚合引发速率及单体转化率的影响,并对固化膜中引发剂残留量进行测定。结果表明:随着光强的增大,单体的双键转化率和聚合速率都增加;二官能度单体的双键转化率和聚合速率高于多官能度单体。4-MA-MBP的质量分数从0.2%增加到1.4%时,单体的双键转化率和聚合速率都明显增加,诱导期缩短,继续增加到1.8%时,双键转化率和聚合速率反而下降;由于可交联在固化膜中,4-MAMBP在固化膜中的残留远低于二苯甲酮。     

含氟二苯甲酮类光引发剂的合成及其光聚合性能研究

以4-（2,3-环氧丙氧基）二苯甲酮与全氟辛酸为原料制备了含氟光引发剂十五氟辛酸1-（4-苯甲酰一苯氧甲基）-2-羟基乙酯（EBPFOA）。通过红外光谱（FT—IR）和核磁共振（伸FNMR）对EBPFOA进行了结构表征;通过紫外吸收光谱测定了EBPFOA的紫外光吸收能力;采用实时红外光谱（RT-IR）考察光强和光引发剂浓度等对EBPFOA单体的双键转化率和聚合速率的影响,并研究了其抗氧阻聚性能。结果表明,随着光强的增加,单体的双键转化率和聚合速率增加;在一定的范围之内,引发剂的浓度越高,双键转化率越高,聚合速率越快,并具有良好的抗氧阳聚性。     

温度对1,6-己二醇二丙烯酸酯紫外光聚合的影响

对在低温下呈固态的1,6-己二醇二丙烯酸酯体系进行紫外光辐照，并用近红外光谱技术研究聚合体系的光聚合及后固化行为，用顺磁共振光谱技术证明后固化过程自由基的衰竭现象，从而探讨1,6-己二醇二丙烯酸酯在固态下进行紫外光聚合的聚合动力学。实验发现固态1,6-己二醇二丙烯酸酯体系可以进行光聚合，并伴有后固化现象；升高反应温度可提高双键转化率；引发剂1173的含量对体系聚合程度有较大影响。     

两种裂解型有机硅大分子光引发剂的合成与性能

以2-羟基-2-甲基-对羟乙基醚基苯基丙酮-1(2959)和氨基硅油为原料合成了双官能度和四官能度两种裂解型有机硅大分子光引发剂NH2-2959-2和NH2-2959-4。研究了两种光引发剂的紫外吸收和降解,引发光聚合及自上浮性能。结果表明,两种光引发剂均在275 nm有最大吸收峰,紫外吸收峰强度随着紫外光辐照时间的延长逐渐减弱。NH2-2959-4光引发剂体系的光聚合速率明显高于NH2-2959-2体系。与小分子光引发剂2959相比,NH2-2959-2和NH2-2959-4均具有较好的自上浮能力,可以在体系中自发地向表面迁移,形成浓度的梯度分布。     

UV光聚合法合成高吸水性树脂中光引发剂的影响

UV光聚合法合成聚丙烯酸-丙烯酸钾(钠)高吸水性树脂,对比于传统的热聚合方法具有工艺简单、反应时间短、易操作、可在常温下进行以及无三废污染等优点。光引发剂是影响UV光聚合反应最重要的因素。本工作对Iragure65l、Iragure819、Iragure184、Iragure1700、Iragure1800、Iragure2929等光引发剂的光引发进行了研究,包括光引发剂的种类、浓度和曝光时间等因素对光聚合体系及产品的吸水性能的影响。结果表明,用Iragure651和Iragure1700为光引发剂聚合效果最好。在相同的聚合条件下,以Iragure651为光引发剂合成的丙烯酸-丙烯酸钾高吸水树脂吸水率可达1358mL/g,吸盐水率可达115mL/g。     

酰基膦氧化物光引发剂在UV光聚合法合成高吸水树脂中的应用

介绍了Irgacure819、Irgacure1800和Irgacure1700三种新型的酰基膦氧化物光引发剂,用紫外．可见分光光度等方法探讨了其结构及光分解的机理。这三种高效的光引发剂可用于紫外光(UV)光聚合法合成聚丙烯酸-丙烯酸铵高吸水树脂。对曝光时间和光引发剂含量对树脂的吸水性能的影响进行了综合比较。以Irgacure1700为光引发剂,UV光聚合法合成的高吸水性树脂,其吸水率最高可达835mL／g,交联率达到94．5％。     

引发体系对聚氨酯丙烯酸酯混杂光固化体系感光性能的影响

研究了自由基型光引发剂Irgacure651和Irgacure1700分别与阳离子型光引发剂SR-1012的质量二芳基碘鎓盐(SR-1012)组成的复合引发体系的配比及用量,以及它们对聚氨酯丙烯酸酯与三乙二醇二丙烯酸酯(TEGDA)、环氧化合物EPON-812组成的混杂光固化体系感光性能的影响。结果表明,Irgacure1700与SR．1012组成的复合引发体系比Irgacure651与SR-1012组成的复合引发体系引发效果好,体系感度可达2．64mJ／cm^2。两种自由基光引发剂配比为2：1时,两种聚合的速率配合较好,体系感度较高,可达6．28mJ／cm^2。引发剂用量在4％-6％比较适宜。混杂体系在276nm和333nm处有响应峰。     

基于示波器的数字化能谱仪构建

针对正电子寿命测量中能量窗口调节较为繁琐的特点,论文基于高分辨数字示波器LeCroy HDO6104和PC,使用MATLAB软件搭建了数字化能谱测量系统,可对BaF_2探测器阳极输出信号进行实时处理和分析。通过对比最大脉冲幅度、曲线拟合与波形面积等方法,选出了最佳的能谱测量方法,实现了数字化的~(22)Na能谱测量及能量窗口调节功能。     

Mol 7C experiments on local fault propagation in irradiated LMFBR fuel subassemblies

The consequences of local cooling disturbances in irradiated fuel pin bundles of Liquid Metal Fast Breeder Reactors (LMFBRs) were investigated in two in-pile experiments in the BR2 reactor at Mol/Belgium. A porous local blockage was used to initiate the fault. This caused severe local fuel pin damage, but there was no fault propagation to major parts of the bundles during four hours of full power operation. If such events occurred in a LMFBR, the delayed neutron detection (DND) signals generated by the fault would be sufficient to initiate reliable automatic shutdown of the reactor.     

Experimental investigation of reaction behavior between carbon dioxide and liquid sodium

Reaction behavior of carbon dioxide (CO₂) with a liquid sodium pool was experimentally investigated to understand the consequences of boundary tube failure in a sodium-CO₂ heat exchanger. In this study, two kinds of experiments were carried out to investigate the reaction behavior.In one experiment, about 1-5 g of liquid sodium pool were poured into flowing CO₂ to obtain the information mainly about the thermo-chemical conditions to initiate the reaction and the chemical constituents of reaction products. During the experiment, visual observation was made using video-camera and the temperature change of the sodium pool and near the surface was measured by thermocouples. The experimental parameters were the sodium pool diameter, the initial temperature of sodium and CO₂, the CO₂ flow direction against pool surface, and the initial moisture concentration in CO₂. The solid products of sodium-CO₂ reaction were sampled and analyzed by X-ray diffraction (XRD), energy dispersion X-ray analysis (EDX), total organic carbon analysis (TOC), and chemical analysis. The reaction gas products were also sampled and analyzed by gas chromatography.In the other experiment, CO₂ was injected into about 200 g of liquid sodium pool to simulate the boundary failure in the sodium-CO₂ heat exchanger. The CO₂ was fed through a helical coil-type tube dipped into the pool to adjust the temperature to the sodium pool temperature, and injected upward into the pool from a pool bottom using a nozzle attached at the end-side of the tube. The experimental parameters were the initial temperature of sodium, the diameter of the nozzle, the flow rate and the injection time of CO₂. The temperature change of sodium pool and the cover gas was measured by thermocouples during the experiment, and the reaction products were sampled and analyzed by the same manner as in the former experiments after the experiment.From these experiments, it became clear that the exothermic reaction occurred above a threshold temperature, and useful and indispensable information such as the resulting temperature and pressure rise and the behavior of solid reaction products in the pool was obtained to evaluate the consequences of boundary tube failure incident in a sodium-CO₂ heat exchanger.     

Fractographic and microstructural characterization of irradiated 304 stainless steel intergranularly fractured in inert gas

Fractographic and microstructural examinations were performed by scanning and transmission electron microscopy, respectively, and correlated, for the thermally sensitized 304 stainless steel (SS) irradiated to 1.2×10²¹ n/cm² (E>1 MeV) in BWR condition and fractured intergranularly in 290 °C inert gas. Intergranular (IG) cracks were present in the specimen surface region and the fracture surface periphery. The fractography showed IG facets decorated with various patterns of linear features/steps. The microstructures of the surface region revealed linear features/deformation twinning near grain boundaries and microtwins at grain boundaries. The linear features identified on the [1 1 1] habit plane varied depending on deformation levels. The high number density of microtwins evidences a high local stress and strain concentration, which may nucleate and initiate at the impingement of deformation twins and grain boundaries. Therefore we conclude that a mechanism causing the IG cracking mechanically in non-aqueous environment is present in the highly irradiated austenitic SS.     

E-beam degradation of thiamphenicol and florfenicol

<正>Thiamphenicol(THA) and florfenicol(FLO) aqueous solutions were irradiated to different doses by 1 MeV electron beams,and redox reactions of THA/FLO and radicals of OH,e_(eq)~- and ~·H were investigated under various conditions.The results showed that at 8 kGy,the decomposition rate of THA and FLO was 97.2%and 98.5%, respectively.Quantitative and qualitative analysis indicated that OH played a key role in E-beam degradation of the THA and FLO in aqueous solutions,and e_(eq)~- and ~·H radicals could initiate the degradation,too.Seven primary products of the THA and FLO degradation were identified.These indicate that E-beam radiation is an effective method to reduce THA and FLO in aqueous solutions.     

Simulation of the chernobyl accident

An analysis of the April 26, 1986 accident at the Chernobyl-4 nuclear power plant in the Soviet Union is presented. The peak calculated core power during the accident was 550 000 MW_t. The analysis provides insights that further understanding of the plant behavior during the accident. The plant was modeled with the RELAP5/MOD2 computer code using information available in the open literature. RELAP5/MOD2 is an advanced computer code designed for best-estimate thermal-hydraulic analysis of transients in light water reactors. The Chernobyl-4 model included the reactor kinetics effects of fuel temperature, graphite temperature, core average void fraction, and automatic regulator control rod position. Preliminary calculations indicated the effects of recirculation pump coast down during performance of a test at the plant were not sufficient to initiate a reactor kinetics-driven power excursion. Another mechanism, or “trigger” is required. The accident simulation assumed the trigger was recirculation pump performance degradation caused by the onset of pump cavitation. Fuel disintegration caused by the power excursion probably led to rupture of pressure tubes. To further characterize the response of the Chernobyl-4 plant during severe accidents, simulations of an extended station blackout sequence with failure of all feedwater are also presented. For those simulations, RELAP5/MOD2 and SCDAP/MOD1 (an advanced best-estimate computer code for the prediction of reactor core behavior during a severe accident) were used. The simulations indicated that fuel rod melting was delayed significantly because the graphite acted as a heat sink.     

Elastic-plastic finite element analyses of stable crack growth and fracture instability in a girth welded pipe

Detailed elastic-plastic finite element fracture mechanics analyses were conducted on a 16 inch diameter Type 304 stainless steel pipe containing a circumferential through-wall crack located in a girth weld. Calculations were performed to analyze the welded pipe treated as (1) a monolithic pipe entirely composed of the base metal, and (2) a composite of base metal and weldment. In the latter, each constituent was assigned distinct mechanical and fracture properties. In both solutions applied J values were calculated for a fixed axial load combined with a monotonically increasing applied bending moment. The material J-resistance curves appropriate for the two problems were each used to initiate and grow the initial crack in a stable manner until fracture instability occurred under load control. It was found that the extent of stable crack growth and the applied loads at fracture instability are distinctly different in the two analyses. It is concluded that more precise fracture mechanics approaches than those now in current use are required for accurate assessments of weld cracking problems.     

Evaluation method of corrosion lifetime of conventional stainless steel canister under oceanic air environment

Natural exposure and accelerated corrosion tests of conventional stainless steels for canisters of Types 304, 304L, and 316(LN) for concrete casks were conducted using several test specimens and 1/5 scale canister models. The welding residual stress of a full-scale model canister was also measured and the lifetime of sealability of canisters against corrosion evaluated. The maximum pitting rate and crevice corrosion rate of Type 304 were approximately 20 and 30 μm/year. Many SCC in the 4 Point Bending (4PB) test specimens were found to initiate from the bottom of the corrosion area by pitting or crevice corrosion. The SCC propagation rates in Types 304 and 304L under natural conditions were around 1.2E−12 to 1.8E−11 m/s in the K (Stress Intensity Factor) range of 0.6–9.0 MPa m^1/2, and that of the accelerated test (60 °C, 95% RHS, filled with NaCl mist) around 1.0E−10 to 3.5E−9 m/s in the K range of 0.5–30 MPa m^1/2. The SCC propagation rates under both natural and accelerated conditions were independent of K. The lifetime of sealability estimated from 1/5 scale models was longer than that from the small bending test specimens and has a safety margin as a structure.     

80MeV/u 12C6+离子辐照小鼠头部对脾脏细胞周期分布的影响

研究重离子辐照小鼠头部对脾脏细胞周期分布的影响，为重离子放射治疗癌症和太空防护提供基础数据。80MeV／u能量的^12C^6＋对BALB／c小鼠头部给以0、0．5、1、2、4、10Gy的照射，用流式细胞仪测脾脏细胞周期分布。重离子辐照后36h，小鼠脾脏细胞S期细胞随着辐照剂量的增加显著减少（p〈0．05）；0．5Gy组、4Gy组和10Gy组出现G0／G0期阻滞明显阻滞（p〈0．05），1Gy组和2Gy组无显著变化（p〉0．05）；0．5Gy组G2／M期细胞显著减少（p〈0．01），其它剂量组明显阻滞（p〈0．05）。重离子辐照小鼠头部对小鼠脾脏细胞周期分布有明显影响。     

Dynamics of oscillatory plasma flows prior to the H-mode in the HL-2A tokamak

This paper discusses edge oscillatory plasma flows, geodesic acoustic mode(GAM) and limit cycle oscillations(LCOs), which have been measured by Doppler reflectometry prior to the high confinement mode(H-mode) in the HL-2A tokamak. The complex relations between the flows and background turbulence have been analyzed. It was observed that the GAM and LCO coexist,and these two flows and turbulence have strong nonlinear interactions during the intermediate confinement phase(I-phase). Dynamics of the shear flows and turbulence prior to the H-mode shows that the oscillatory flows quench the turbulence along with the increase of the mean E × B flow at the early stage of the I-phase, then the oscillatory flows are damped and the further increased mean flow takes over the role in turbulence suppression. The reduced turbulent transport results in the formation of a steep edge transport barrier. It suggests that the oscillatory flows can initiate the L–H transition through providing a positive feedback for the increase of the mean E × B flow strength.